Egan points out that one difficulty with stopping access to web pages with indecent content involving children, is that paedophilic offenders may find euphemisms and code words to tag photographic content, so only they know them. Then the authorities would be always playing 'catch up' to them.

How do you spot a paedophile? With great difficulty. While media coverage of cases of horrific child abuse and murder use terms such as 'evil', 'monster' and 'fiend' to describe perpetrators, the reality is that paedophiles generally look the same as everybody else.

Stuart Hazell, 37, was a man with a violent and scarred background which is nothing unusual in such crimes. But, tellingly, he also had an addiction to images of children being sexually abused. Police discovered hundreds of such pictures on his computer hard drive. He had also visited websites searching under 'illegal incest pics' and 'sex with young children'.